The same photo of Tibouchina heteromalla on wiki is on flickr, T. grandiflora is mentioned there as being a synonym..
http://www.flickr.com/photos/c...
Tibouchina heteromalla from Brisbane Botanic gardens
http://www.flickr.com/photos/t...
http://www.flickr.com/photos/t...
I have found some on flickr with flowers like yours Myriam, in some cases they have been named Tibouchina heteromalla or grandiflora, but in cases where the flowers match those of the examples from botanical gardens there has usually been a certain person confirming the name but I haven't seen this person confirm any others. Some others with flowers like yours haven't been given a species name.
These confirmed by the same person..
http://www.flickr.com/photos/g...
http://www.flickr.com/photos/c...
I have come across two examples of Tibouchina granulosa which look much like yours, but the majority of photos are very different so I think this is another case of mis-naming.
http://www.flickr.com/photos/6...
http://cityinagarden-jyoti.blo...
There's drawings of both on delta-intkey but neither look like yours!
http://delta-intkey.com/angio/...
